NILJON Base w/ LMR-400 ?

[airforceflyr]

Anyone using the NILJON Super-M Base with LMR-400 ? I've called several dealers attempting to have custom made 50 ft with PL-259---> F connector. Apparently the F connector is not big enough to support the width of the LMR-400.

What are other Niljon users using for low-loss cableing ? Thanks !

Clay

 

[scannerfreak]

That would be me..I use the Super M Base with LMR-400 30' up. I had them put on PL-259's(UHF) as that is what the Super M uses.

I then added a low loss adapter for the PL 259 to BNC. I purchased them all from Texas Towers..

By far the best antenna setup I have ever had..I'm thinking of going to LMR-600. I believe LMR-600 only come in N connectors..

Hope this helps...

 

[airforceflyr]

Many thanks ! So you have the PL259-->BNC directly to the back of the radio ? For my setup, I would like to hit an antenna multicoupler first (ref the F connector) then go BNC to the recv'er.

Wondering if I can go from the Antenna--> PL-259-->F--> Coupler--->BNC(radios) without incurring serious cable/connector loss ?

I will call Tx towers tommorow and ask if they can build a LMR-400 with PL-259-->F

Clay

 

[scannerfreak]

Many thanks ! So you have the PL259-->BNC directly to the back of the radio ? For my setup, I would like to hit an antenna multicoupler first (ref the F connector) then go BNC to the recv'er.

Wondering if I can go from the Antenna--> PL-259-->F--> Coupler--->BNC(radios) without incurring serious cable/connector loss ?

I will call Tx towers tommorow and ask if they can build a LMR-400 with PL-259-->F

Clay

You'd have to look at the loss for the extra connectors(s),,I have mine PL 259-to BNC right into the back of my Pro-2096 and it works like a champ

If Texas Towers doesn't have the adapter(s) you want try Here.

Also, here is an attenuation chart for LMR cables..What I found out is, there is a huge difference(3.9 to 2.5 per 100') in the 800 MHz band between 400 and 600..This is why I'm thinking about upgrading..

 

[n4voxgill]

If you are spending the money for LMR, why not spend a little more and get a Stridesburg multicoupler that uses BNC

 

[MacombMonitor]

Many thanks ! So you have the PL259-->BNC directly to the back of the radio ? For my setup, I would like to hit an antenna multicoupler first (ref the F connector) then go BNC to the recv'er.

Wondering if I can go from the Antenna--> PL-259-->F--> Coupler--->BNC(radios) without incurring serious cable/connector loss ?

I will call Tx towers tommorow and ask if they can build a LMR-400 with PL-259-->F

Clay

I think the whole "loss" factor is more of an issue when transmitting, and not a serious issue for receivers.

 

[scannerfreak]

I think the whole "loss" factor is more of an issue when transmitting, and not a serious issue for receivers.

Huh? How did you arrive at that? Just curious...

 

[MacombMonitor]

I think the whole "loss" factor is more of an issue when transmitting, and not a serious issue for receivers.

Huh? How did you arrive at that? Just curious...

When you're putting higher levels of RF power on the antenna system, small problems become more pronounced. Similar is all the concern about using 50 ohm coax, for the proper impedence match. Again, this is very important when transmitting, but 75 ohm cable TV coax works just find for receive only applications.

 

[scannerfreak]

When you're putting higher levels of RF power on the antenna system, small problems become more pronounced. Similar is all the concern about using 50 ohm coax, for the proper impedence match. Again, this is very important when transmitting, but 75 ohm cable TV coax works just find for receive only applications.

Of course it will work..That's not what we are talking about..We are talking about loss of dB's when using connector adapters.. :roll:

If a really weak signal is received at the antenna, but a poor choice of cable/and or connectors are used, it's possible that it may attenuate the signal such that the receiver is unable to detect it.

So if you use good cable/and or connectors, you WILL hear more signals.

Most good quality connectors attenuate the signal very little (0.1-0.3 dB) but some can be horrible (1-3 dB)! So if you use more than one, it could be as bad as selecting a poor type of coax.

If you don't think that's a "serious issue for receivers",I'd hate to see you're setup

 

[Al42]

When you're putting higher levels of RF power on the antenna system, small problems become more pronounced.

Yep - when you put 100 watts into a cable that causes a 50% loss, you lose 50 watts, but when you put 1 milliwatt into that cable you only lose 1/2 milliwatt.

But you still lose half the signal.

Similar is all the concern about using 50 ohm coax, for the proper impedence match. Again, this is very important when transmitting, but 75 ohm cable TV coax works just find for receive only applications.

Except that the loss, in percentage, is the same, transmitting or receiving. If you want to spend money for antenna gain, then throw it away with cheap cable, go ahead. Some of us would rather spend the money and keep the signal.

 

[MacombMonitor]

When you're putting higher levels of RF power on the antenna system, small problems become more pronounced. Similar is all the concern about using 50 ohm coax, for the proper impedence match. Again, this is very important when transmitting, but 75 ohm cable TV coax works just find for receive only applications.

Of course it will work..That's not what we are talking about..We are talking about loss of dB's when using connector adapters.. :roll:

If a really weak signal is received at the antenna, but a poor choice of cable/and or connectors are used, it's possible that it may attenuate the signal such that the receiver is unable to detect it.

So if you use good cable/and or connectors, you WILL hear more signals.

Most good quality connectors attenuate the signal very little (0.1-0.3 dB) but some can be horrible (1-3 dB)! So if you use more than one, it could be as bad as selecting a poor type of coax.

If you don't think that's a "serious issue for receivers",I'd hate to see you're setup

Currently I don't have, or really need outside antennas. Although I'm now considering installing a couple to get better reception from Selfridge Air Base. You got my attention, and I started reading up on various coax, connectors, and loss. You are correct, that cable, and connectors can affect reception more than I had originally thought.

I notice you are using the Mil-Jon base antenna. After all you pointed out, why did they put a SO239 connector on it? From what I've read, the SO239 is designed for up to 200MHz. The antenna is claimed to be good for up to 1300MHz. It seems that an N connector would have been a better choice.

More confusing, the AOR DS3000A discone rated for up to 3,000MHz, comes supplied with N connectors on both ends of it's cable, but they use RG58A/U cable! Icom does the same thing with their discone, the AH7000.

 

[Al42]

After all you pointed out, why did they put a SO239 connector on it? From what I've read, the SO239 is designed for up to 200MHz. The antenna is claimed to be good for up to 1300MHz. It seems that an N connector would have been a better choice.

Ns are more expensive to buy, and more expensive to install.

More confusing, the AOR DS3000A discone rated for up to 3,000MHz, comes supplied with N connectors on both ends of it's cable, but they use RG58A/U cable! Icom does the same thing with their discone, the AH7000.

58 is cheaper.

Most questions of this type tend to be answered if you look at which department, technical or financial, makes the company's decisions. Since design is considered an expense, not a profit center, it gets very little say in things of this nature.

When a company uses good coax or good connectors (or modifies its product because the users prefer it to be made differently - thank you Uniden), you know you're dealing with one of the shining knights.

 

[brwkem]

If your going with an LMR 400 setup would it be better to go with N connectors on both ends so as to be able to change to different antenna if you want down the road instead of be ing dedicated with a PL 239 connector?

 

[airforceflyr]

Received the NILJON base last week. My 50ft of LMR-400 (PL-259--> BNC) is still enroute, so I decided to temporary mount it where my Scantenna had formerly been. This setup is 50ft RG-6 Quad Shield from Rat Shack with F-->SO-239 on one end and F-->BNC on the recv end. The results so far (on UHF Milair, my primary target) are that the Scantenna seems to pull in weaker airborne targets, while they are about even with ground transmitters (ATC, Tower etc). I'm anxious to see if the LMR-400 with the correct plug (PL259) will substantially improve my UHF reception.

Thoughts ?

Clay

 

[brwkem]

Where did you order your LMR 400 from?

 

[remedy44]

Hi all here are the connectors i use on my scanners with LMR-400 http://www.rfparts.com/c-bnc.html
part # RFB-1101-1SI

Happy Scanning

Where did you order your LMR 400 from?

I ordered mine from AESHAM 500ft roll $237 + some change

 

[kb2vxa]

Hi guys,

Without getting all technical on you the connectors are immaterial when it comes to insertion loss unless you're trying to use a PL-259 on SHF. In this case the lumped impedance it introduces is unacceptable because it causes a reflection at that point raising the SWR. Since it's not a factor in receiving it would only be taken into consideration by purists.

The multicoupler has the greatest insertion loss of the entire system, I would pay particular attention to it and avoid one if possible. A VHF/UHF coaxial switch has negligible insertion loss and is good into low microwave frequencies so is "the weapon of choice" if you don't need a bunch of scanners all going at once.

"Similar is all the concern about using 50 ohm coax, for the proper impedence match. Again, this is very important when transmitting, but 75 ohm cable TV coax works just find for receive only applications."

75 ohm cable terminated in a 50 ohm pure resistive load introduces a 1.5:1 SWR which is perfectly acceptable and is often the best you can get averaged across a particular VHF or UHF band with 50 ohm coax and the average antenna. This makes it suitable for transmitting so the bottom line is loss is the determining factor of which cable is superior to which. Hams have been known to use 75 ohm CATV hardline with excellent results.